Microarray analysis reveals glucocorticoid-regulated survival genes that are associated with inhibition of apoptosis in breast epithelial cells

Cancer Res. 2004 Mar 1;64(5):1757-64. doi: 10.1158/0008-5472.can-03-2546.

Abstract

Activation of the glucocorticoid receptor (GR) results in diverse physiological effects depending on cell type. For example, glucocorticoids (GC) cause apoptosis in lymphocytes but can rescue mammary epithelial cells from growth factor withdrawal-induced death. However, the molecular mechanisms of GR-mediated survival remain poorly understood. In this study, a large-scale oligonucleotide screen of GR-regulated genes was performed. Several of the genes that were found to be induced 30 min after GR activation encode proteins that function in cell survival signaling pathways. We also demonstrate that dexamethasone pretreatment of breast cancer cell lines inhibits chemotherapy-induced apoptosis in a GR-dependent manner and is associated with the transcriptional induction of at least two genes identified in our screen, serum and GC-inducible protein kinase-1 (SGK-1) and mitogen-activated protein kinase phosphatase-1 (MKP-1). Furthermore, GC treatment alone or GC treatment followed by chemotherapy increases both SGK-1 and MKP-1 steady-state protein levels. In the absence of GC treatment, ectopic expression of SGK-1 or MKP-1 inhibits chemotherapy-induced apoptosis, suggesting a possible role for these proteins in GR-mediated survival. Moreover, specific inhibition of SGK-1 or MKP-1 induction by the introduction of SGK-1- or MKP-1-small interfering RNA reversed the anti-apoptotic effects of GC treatment. Taken together, these data suggest that GR activation in breast cancer cells regulates survival signaling through direct transactivation of genes that encode proteins that decrease susceptibility to apoptosis. Given the widespread clinical administration of dexamethasone before chemotherapy, understanding GR-induced survival mechanisms is essential for achieving optimal therapeutic responses.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Apoptosis*
  • Breast Neoplasms / pathology*
  • Cell Cycle Proteins*
  • Cells, Cultured
  • Dexamethasone / pharmacology
  • Dual Specificity Phosphatase 1
  • Epithelial Cells / pathology
  • Female
  • Gene Expression Profiling
  • Glucocorticoids / pharmacology*
  • Humans
  • Immediate-Early Proteins / analysis
  • Immediate-Early Proteins / physiology
  • Nuclear Proteins*
  • Oligonucleotide Array Sequence Analysis*
  • Phosphoprotein Phosphatases*
  • Protein Phosphatase 1
  • Protein Serine-Threonine Kinases / analysis
  • Protein Serine-Threonine Kinases / physiology
  • Protein Tyrosine Phosphatases / analysis
  • Protein Tyrosine Phosphatases / physiology
  • RNA, Small Interfering / pharmacology
  • Signal Transduction

Substances

  • Cell Cycle Proteins
  • Glucocorticoids
  • Immediate-Early Proteins
  • Nuclear Proteins
  • RNA, Small Interfering
  • Dexamethasone
  • Protein Serine-Threonine Kinases
  • serum-glucocorticoid regulated kinase
  • Phosphoprotein Phosphatases
  • Protein Phosphatase 1
  • DUSP1 protein, human
  • Dual Specificity Phosphatase 1
  • Protein Tyrosine Phosphatases